Related Experiment Video
Updated: Jun 19, 2026

Visualizing Bacteria in Nematodes using Fluorescent Microscopy
Published on: October 19, 2012
POSITIVE VARIATIONS IN NITELLA
1Laboratories of The Rockefeller Institute for Medical Research.
Abstract:
The reversible electrical variations hitherto described for plants and animals consist in a reversible loss of positive potential at a stimulated spot by which it becomes more negative. In this paper we describe changes which consist in a reversible loss of negative potential at a stimulated spot whereby it becomes more positive. We suggest that this be called a positive variation. The stimulation was produced in all cases by pinching or bending the cell. This produced a compression wave which traveled along the cell, producing a negative variation at a spot which was positive and a positive variation at a spot which was negative (due to application of 0.1 M KCl). The response produced by the compression wave differs in several respects from an ordinary propagated negative variation and may be termed a positive mechanical variation.
More Related Videos
08:05Measurement of the Potential Rates of Dissimilatory Nitrate Reduction to Ammonium Based on 14NH4+/15NH4+ Analyses via Sequential Conversion to N2O
Published on: October 7, 2020
20:01Single-plant, Sterile Microcosms for Nodulation and Growth of the Legume Plant Medicago truncatula with the Rhizobial Symbiont Sinorhizobium meliloti
Published on: October 1, 2013
Related Concept Videos
Evolution of New Traits in Microbes
Other Nuclides: 31P, 19F, 15N NMR
While fluorine-19 and phosphorous-31 have high natural abundances (100%) and positive gyromagnetic ratios, nitrogen-15 has a low natural abundance and a negative gyromagnetic ratio. However, nitrogen-15 is still preferred over nitrogen-14 (which has a high...
2° Amines to N-Nitrosamines: Reaction with NaNO2
Comparing Copy Number Variations and SNPs
Copy number variations or CNVs are the structural variations that cover more than 1kb of DNA sequence. The single nucleotide polymorphism (SNP), on the other hand, is a single nucleotide change or a point mutation that is found in more than 1%...
Inorganic Nitrogen Assimilation
Single Nucleotide Polymorphisms-SNPs